i have this seiko that the entire face was a photovoltaic cell (solar cell), worked great for a while, as long as you gave it some sun a few moments a day, it would keep ticking, untill i made the mistake of taking it to the land of eternal darkness, england..... london to be exact, it stopped at around 3am, i woke up in the morning, put it on, saw it stopped, exposed it to some sunlight, it started marching again, but i think it suffered some kind of damage, or the battery wasnt supposed to be empty, so every time it lasted less and needed more sunshine to recharge untill it stopped and died, and never charged again,